"Didn't I tell you?" (3)
I believe the answer is:
see
'didn't i tell you?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for see that I've seen before include "Perceive; diocese" , "Salisbury, for one" , "Perceive; meet (someone)" , "Consider; diocese" , "Discern visually" .)